College Algebra, 2013a

170 Linear and Quadratic Functions
23. f(x) =3
slope: m =0
y-intercept: (0, 3)
x-intercept: none
4
3
2
1
y
−2 −1 1 2
x
24. f(x) =0
slope: m =0
y-intercept: (0, 0)
x-intercept: {(x, 0) | x is a real number}
25. f(x) = 2 3 x + 1 3
slope: m = 2 3
y-intercept: ( 0, 1 )
3
x-intercept: ( − 1 2 , 0)
1
y
−2 −1 1 2
−1
2
1
y
−2 1 2
−1
x
x
26. f(x) = 1 − x
2
slope: m = − 1 2
y-intercept: ( 0, 1 )
2
x-intercept: (1, 0)
2
1
y
−2 −1 1 2
−1
x
27. (−1, −1) and ( 11
5 , 27 )
5
28. d(t) =3t, t ≥ 0.
29. E(t) = 360t, t ≥ 0. 30. C(x) =45x + 20, x ≥ 0.
31. C(t) =80t + 50, 0 ≤ t ≤ 8. 32. W (x) = 200+.05x, x ≥ 0 She must make
$5500 in weekly sales.
33. C(p) =0.035p +1.5 The slope 0.035 means it costs 3.5¢ per page. C(0) = 1.5 means there
is a fixed, or start-up, cost of $1.50 to make each book.
34. F (m) =2.25m +2.05 The slope 2.25 means it costs an additional $2.25 for each mile beyond
the first 0.2 miles. F (0) = 2.05, so according to the model, it would cost $2.05 for a trip of 0
miles. Would this ever really happen? Depends on the driver and the passenger, we suppose.